ABSTRACT
Stimulated Raman spectra have been excited in liquid SnCl(4) and in methane gas making use of a medium high-power ruby laser. The spectra have been photographed by means of a high-resolution grating spectrograph. The Deltagamma value approximately nu(1) for methane was found to be 2916.605 cm(-1) +/- 0.012 cm(-1). No detectable pressure shift was observed over a range of gas densities from 3 amagat to 12 amagat. The stimulated Raman lines in methane are very sharp and only slightly broader than the laser line. In SnCl4 the first Stokes line consists of only a single component instead of the expected isotopic triplet. The half-intensity width of this line was found to be 0.5 cm(-1). At least 0.15 cm(-1) of this line-width must be due to the stimulated Brillouin doublet since the threshold is lower for the stimulated Brillouin effect than for the stimulated Raman effect. The stimulated Brillouin effect was observed with a Fabry-Perot etalon. Measurements of the Fabry-Perot patterns gave a value of 840 m per see for the velocity of sound in SnCl(4) at 27 degrees C.
ABSTRACT
Stimulated Brillouin scattering from N(2) and CH(4) using a giant-pulse laser has been observed in an arrangement whereby the laser cannot relase and amplify the back-scattered radiation. This allows a quantitative study of the parameters affecting stimulated Brillouin scattering. The back-scattered beam converges at the same angle at which the laser beam diverges. The Brillouin component can have a narrow spectral width, one-third that of the laser itself, and in some cases can have a duration of only a few nanoseconds. N(2) at high pressure can back-scatter as much as 45% of the incident power. The speeds of sound in CH(4) and N(2) have been measured at lower pressures than were previously reported.
